Hi Humphrey !
You can use my pictures, of course, and if you need I can try to help. I didn't find any plans on the internet for my 13 string guitar, so I made them myself. Wherever possible, the specifications are the same of my 6 string guitar. For the rest of the measures, I made the technical plans myself, and in the end everything worked out fine.
I am very happy with the sound, and the feedback I get from players is always very good ; the problem is that I don't know how to play it !